More clear version of previous namei/pledge/chroot solution. namei flag

KERNELPATH indicates this operation is being done on behalf of the kernel,
not a process, so ignore chroot of the current process context, start at /,
and skip unveil and pledge checks.  Discussed with beck and semarie

diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
index 5a93a8b..eaac8a0 100644 (file)
--- a/sys/kern/vfs_lookup.c
+++ b/sys/kern/vfs_lookup.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: vfs_lookup.c,v 1.73 2018/08/02 04:41:47 beck Exp $    */
+/*     $OpenBSD: vfs_lookup.c,v 1.74 2018/08/13 23:11:44 deraadt Exp $ */
 /*     $NetBSD: vfs_lookup.c,v 1.17 1996/02/09 19:00:59 christos Exp $ */
 
 /*
@@ -171,12 +171,17 @@ fail:
        /*
         * Get starting point for the translation.
         */
-       if ((ndp->ni_rootdir = fdp->fd_rdir) == NULL)
+       if ((ndp->ni_rootdir = fdp->fd_rdir) == NULL ||
+           (ndp->ni_cnd.cn_flags & KERNELPATH))
                ndp->ni_rootdir = rootvnode;
 
-       error = pledge_namei(p, ndp, cnp->cn_pnbuf);
-       if (error)
-               goto fail;
+       if (ndp->ni_cnd.cn_flags & KERNELPATH) {
+               ndp->ni_cnd.cn_flags |= BYPASSUNVEIL;
+       } else {
+               error = pledge_namei(p, ndp, cnp->cn_pnbuf);
+               if (error)
+                       goto fail;
+       }
 
        /*
         * Check if starting from root directory or current directory.

diff --git a/sys/sys/namei.h b/sys/sys/namei.h
index 6a25840..c57dcb8 100644 (file)
--- a/sys/sys/namei.h
+++ b/sys/sys/namei.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: namei.h,v 1.37 2018/08/11 16:16:07 beck Exp $ */
+/*     $OpenBSD: namei.h,v 1.38 2018/08/13 23:11:44 deraadt Exp $      */
 /*     $NetBSD: namei.h,v 1.11 1996/02/09 18:25:20 christos Exp $      */
 
 /*
@@ -146,6 +146,7 @@ struct nameidata {
 #define STRIPSLASHES    0x100000      /* strip trailing slashes */
 #define PDIRUNLOCK     0x200000      /* vfs_lookup() unlocked parent dir */
 #define BYPASSUNVEIL   0x400000      /* bypass pledgepath check */
+#define KERNELPATH     0x800000      /* access file as kernel, not process */
 
 /*
  * Initialization of an nameidata structure.